docs: def split_tarball_path(path):
      '''
      split_tarball_path(path) yields a tuple (tarball, p) in which tarball is the path to the tarball
        referenced by path and p is the internal path that followed that tarball. If no tarball is
        included in the path, then (None, path) is returned. If no internal path is found following
        the tarball, then (path, '') is returned.
      '''
      lpath = path.lower()
      for e in tarball_endings:
          if lpath.endswith(e): return (path, '')
          ee = e + ':'
          if ee not in lpath: continue
          spl = path.split(ee)
          tarball = spl[0] + e
          p = ee.join(spl[1:])
          return (tarball, p)
      return (None, path)